Safety devices for a motor vehicle with a multi-chamber airbag are known in various embodiments and various arrangements. In particular, airbag arrangements in the occupants' front, side, and head impact regions are known. Each of these airbags is inflatable in the event of a vehicle collision, as a function of the collision deceleration and direction, by way of an associated activatable gas generator, in order to intercept an occupant's impact in damped fashion.
One problem with these arrangements is that an inflating airbag can exhibit disadvantageous aggressiveness toward occupants or objects in the inflation region. These problems occur in particular with occupants who are outside of a normal position (out of position), for example, in the case of a child who is standing in front of a seat or an adult who is leaning far forward in a seat, and objects on a seat, for example a child seat attached thereon.
Measurement arrangements are known for detecting such out-of-position situations upon activation of an airbag and optionally preventing an airbag from firing or causing it to do so in reduced fashion. Known in particular for this purpose are distance measurement arrangements operating in non-contact fashion with infrared and/or ultrasonic sensors and weight sensors. These arrangements are complex and expensive.
A safety device is described in, for example, European Patent Application No. 0 812 741. In this safety device, a sensing medium is associated with a front part of the airbag, which is configured as a gas bag. The medium is configured to participate in the advance movement of the airbag. An analysis device is provided for determining the advance velocity of the sensing medium and, therefore, of the airbag moving into the passenger compartment. The advance distance and/or the advance times detected by the analysis device may be used to influence the filling behavior of the airbag to thereby reduce the gas volume or suppress gas delivery. A similar operating mechanism is described in European Patent Application No. 0 836 971.
It is an object of the present invention to develop a safety device for a motor vehicle with a multi-chamber airbag in such a way that its aggressiveness is reduced with a simple and directly acting system for recognizing an out-of-position situation.